Abstract: A new technology of producing polymeric aluminum chloride coagulant from kaolin has been presented in this paper.The influence of process parameters such as roasting temperature、roasting time、concentration of hydrochloric acid、time of acid immersion are studied,the conditions of producing PAC are determined:The kaolin roasts in 650℃～800℃ for 2.0～2.5 hours;then is immersed 15%～20% hydrochloric acid for 2～3 hours at 100℃ in normal pressure;the proportion of kaolin to acid is 1.0∶1.0～1.5.The coagulant contains Al₂O₃ 12 46%,Fe₂O₃ 0.31%,density 1.287g/cm³,alkalinity 55 6%.